Semiconductor wafers composed of silicon are generally subjected to a process of chemical mechanical polishing (CMP) for smoothing one or both sides of the semiconductor wafer. After the polishing process, the semiconductor wafers are contaminated with residues of the polishing agent and have to be cleaned. The residues have to be removed as rapidly as possible since they can attack the sensitive surface of the semiconductor wafer, and they have to be removed as completely as possible since particles remaining on the cleaned surface can cause surface defects which can no longer be removed later by cleaning. Furthermore, the cleaning must also be completed in the shortest possible time for economic reasons.
DE 10 2007 032 385 A1 describes a method for cleaning a semiconductor wafer after CMP in a modularly structured cleaning installation. The method provides for semiconductor wafers each individually being cleaned in at least two cleaning modules and dried in a drying module. A cleaning sequence which comprises three substeps and is aimed at removing metallic impurities is carried out in the same cleaning module.
In EP 0 708 480 A1, as an advantageous alternative to cleaning using a cleaning solution containing ammonium hydroxide, hydrogen peroxide and water, it is proposed that a semiconductor wafer, after a polishing process, is firstly cleaned using an aqueous solution of hydrofluoric acid, then rinsed using ozone-containing water, and finally cleaned using brushes in the presence of water.
U.S. Pat. No. 5,944,906 describes a method by which semiconductor wafers whose surfaces are formed by at least two different materials are cleaned after a polishing process. When this method is employed, the semiconductor wafer is successively treated with a series of aqueous cleaning solutions. The series comprises hydrofluoric acid, a surfactant solution having a pH in the range of 1 to 4, an aqueous ammonium hydroxide solution, a surfactant solution having a pH in the range of 8 to 10, and deionized water.